What apps still run on your old iPhones? Only the fully local camera, photos and music apps run on my iPhone 4. A very limited number of web sites still load in Safari. How will we demo these old phones to the next generation?

I haven't written about which apps still work on my old iPhones today, so I can't give you a real inventory. But your experience matches what you'd expect: the fully local apps (camera, photos, music) keep working because they don't depend on servers, certificates, or web standards that have moved on without them. Anything that talks to the network slowly turns into what I once called a "zombie UI" when an iOS beta ate most of my apps.

I've kept old devices around for exactly this kind of comparison. Back in 2013 I was running iOS 3, 4, 5, 6, and 7 on devices in the office at the same time. Those were working test devices then. Now they'd mostly be museum pieces.

How do you demo them to the next generation? I've had the most luck putting old and new side by side. In talks, I've walked through the iPhone camera app version by version. The first one let you take a picture and look at it, and that was it. Then came video, the front camera (enter... selfies), flash, grids, HDR, and square photos from the Instagram era.

Since the camera still runs locally on your iPhone 4, it's actually a great live demo. Hand someone the old phone and their current one and let them feel the difference. App counts work too: the original iPhone shipped with 16 Apple apps, and the iPhone Duo comes with 48.

So, for demos, stick to the apps that still run on their own and let the side-by-side comparison show how much has changed.